Concrete components and their production are known. It has been familiar practice for some time to provide such concrete components with insulating elements during their production. The concrete components concerned are frequently panel-shaped, meaning that connections between insulation panels and concrete panels are often involved. Sandwich panels, as they are called, are also frequently produced, in which the insulation layer is sandwiched between two layers of concrete.
Particularly during the preparation of such sandwich elements, the question of a firm connection between the two (exterior) layers of concrete arises, as this connection must pass through the insulation layer without causing a thermal bridge of notable extent.
To this purpose the US20040065034A1 discloses a sandwich element comprising a woven carbon fibre grid connecting two outer concrete layers and passing through a insulation layer. The carbon fibre grid is integrated in somewhat long insulation elements and extends in a plain perpendicular to the surface of the sandwich element. The method for producing such sandwich elements aims primarily in making use of existing fabrication methods for being able to produce great numbers of sandwich elements in a flexible and inexpensive manner. The US20040206032A1 is a “Continuation-in-part” of US20040065034A1. In further developing the US20040065034A1 the US20040206032A1 concentrates on the connection of sandwich elements to one another and to the connection of sandwich elements to buildings. The carbon fibre grids used are the same as in US20040065034A1, see corresponding name of the trademark of the grids.
The EP0532140A1 discloses sandwich elements comprising fiber-reinforced synthetic parts connecting two outer concrete layers. The fiber-reinforced synthetic parts are fixed to tensioned steel ropes connected to a formwork. In some embodiments the fiber-reinforced synthetic parts that are longwise and extend in most cases in one single plain are integral with insulation material The method for casting the sandwich elements discloses different and independent steps for inserting the reinforcement of the concrete layers and for inserting the longwise fiber-reinforced synthetic parts for the connection of the concrete layers.
The DE 100 07 100 B4, among other publications, addresses this problem. It discloses a method in which, to start with, a first concrete layer is formed. Elements for connecting the first concrete layer with the second concrete layer to be added later are applied onto this layer. These rise up perpendicular to the second layer, piercing the insulation layer when this is applied onto the first concrete layer. Pour-in-place PU foam is then used to seal the holes again. Finally, the second concrete layer is poured onto the insulation layer.
The DE 10 2012 101 498 A1, which was not yet part of the prior art when the original application for the present invention was filed, also discloses a sandwich element of such kind, in which the two concrete layers are connected by reinforcing elements that pass through the insulation layer. A method of producing the disclosed component is also described in the last-mentioned publication.
What the two aforementioned publications have in common is that the use of non-metallic reinforcing elements is mentioned.
Practical experience in the production of concrete components shows that specific problems arise from the use of textile reinforcing elements, such as glass fibres or carbon fibre elements. For example, these reinforcing elements weigh less and have a lower compressive strength than metal. The tensile strength of the materials is often anisotropic, and pre-hardened reinforcing grids are very fragile.
The aforementioned low weight can cause reinforcing material applied onto a concrete layer to float up, preventing it from forming close contact with the concrete matrix. One way of avoiding this problem consists in weighting down the fragile reinforcing material with stones or metal put on top, thereby ensuring that reinforcing members remain in the concrete matrix when it sets. With this method, however, reinforcing members sometimes assume a position too close to the bottom of the shell mould (they sink too deep on account of the weighting) and later shine through the finished layer of concrete. This is particularly undesirable in the case of facade units. The distance between the bottom of the mould and the reinforcing constituents is therefore often set by placing the latter on spacers supported on the bottom of the mould.
The disadvantages of this measure are the fact that the spacers are visible at the surface of the first concrete layer, the effort and expense, and the imponderables associated with rather delicate measures of this kind, both during the production of poured-in-place (PIP) concrete components and in the case of prefabricated elements.